We're now in April in New England and next week my lawn guy will be doing his power raking as part of his spring cleanup.
My question is this: I would like to lay down some perennial ryegrass overseed as my lawn was thin last year.

I have a contract with a lawn service and they are set to apply their step 1 fertilizer which has crabgrass preventer. I asked if the crabgress preventer will kill my new seeds, and they said I should be OK, as long as my new ryegrass seed has had two weeks to germinate...Is this right?

Obviously, I don't want to lay down a bunch new seed today, and have it germinate, only to have my pre-emergent laid down two weeks later and kill it.